It used to be considered gout was the result of culinary excess and old port wine.

Today it is recognised as an affliction even the poor and under-nourished can suffer from even if they have never tasted old port wine and jugged hare.

Clearly excess should be avoided but unless the gout condition is acute and ordinary anti-inflammatory drugs and pain-killers aren't providing relief there are no specific foodstuffs to avoid; to the best of my knowledge as I wasn't advised to avoid anything when my attack of gout was diagnosed and I had a close friend who suffered from gout in his hands quite a lot who also had no special dietary requirements.

The legendary Mrs. Beeton had a recipe for "quick gravy" that didn't use traditional ingredients. I am sure you will find it fascinating.

More recently something called gravy salt was extensively used to provide extra colouring of the meat stock before thickening with flour.

Licorice extract has been used extensively to colour many products and I feel it could be used safely as a component of a meat-free gravy.
Onion gravy is a traditional thing that is usually a standard meat-based gravy with added onions. My gravy used to also contain interesting lumps that turned out to be peas, beans and mushrooms.

I have a vegetarian friend and her gravy mostly is something like pineapple juice that is flavoured with spices and thickened.

Colouring plain water and flavouring it with herbs, seasoning and onions before thickening would probably make a passable gravy. Lentils could perhaps be used for the thickening instead of flour.